Product Details:
- Size range: 8–100mm (up to 140mm)Band width: 9 / 12 / 12.7mmRecommended torque: 4.0–5.1 NmSafe max torque:5.6 NmUltimate torque≥ 6.8 NmMaterials304 / 316 (W4 / W5)
How to Measure: Why Hose OD, Not Hose ID
Worm gear clamps size by the outside diameter (OD) of the hose at the joint — measured over the fitting, barb or nipple that the clamp must grip. The printed hose size (e.g. “3/4″” or “19mm”) is the internal bore and will under-size your clamp. Assemble the hose onto the fitting exactly as it will be installed. Measure the outer circumference of the hose over the fitting with a tape, then divide by π (3.14) to get OD — or use a caliper directly. Add ~2–3mm clearance so the clamp band can close freely around the joint. Pick the clamp range that places your measured OD in the middle third of its adjustment span.
Band Width: 9mm / 12mm / 12.7mm (1/2″)
Band width | Best for | Notes |
|---|---|---|
9mm | Small hoses ~8–32mm OD; automotive vacuum/coolant/fuel; tight spaces | Lower profile, lighter; typical tightening 3.0–4.5 Nm |
12mm | Hoses ~20mm OD and above; silicone hoses; general industrial | Most common DIN 3017 width; good balance of grip and flexibility |
12.7mm (1/2″) | American-type (SAE J1508 style) clamps; agricultural, marine, HVAC | Wide band distributes force over more surface; 5/16″ screw |
Material Grades: W1, W2, W4, W5 Explained
| Grade | Band & Housing | Screw | Corrosion rating | Typical use |
|---|---|---|---|---|
| W1 | Carbon steel, zinc-plated | Carbon steel, zinc-plated | Fair — indoor | Low-cost general purpose; dry environments |
| W2 | Stainless steel (AISI 201/301/304 or 430) | Plated carbon steel | Good | Automotive coolant / engine bay; cost-sensitive OEM |
| W4 | Stainless steel AISI 201/301/304 | Stainless steel AISI 201/301/304 | Very good | Standard spec: automotive, plumbing, industrial, food processing |
| W5 | Stainless steel AISI 316 | Stainless steel AISI 316 | Excellent | Marine, coastal, chemical, high-humidity |
Installation in 5 Steps
- Slide the clamp onto the hose before connecting to the fitting; position the housing clear of the barb.
- Push the hose fully onto the fitting until it seats against the shoulder or stop ring.
- Position the clamp over the barb (not past it) — the screw housing should sit where the band can compress the hose onto the ridge.
- Tighten to the recommended torque for your band width (see Table above); stop before the max 5.6 Nm.
- Verify by feel and re-check later: the band should be firm with no gap, and the screw should not be at its limit; retighten after the first heat cycle.
FAQ
1. What size worm gear clamp do I need for a 25mm hose?
Measure the hose outside diameter over the fitting. A 25mm OD typically fits a 25–40mm clamp — select a range where your OD falls in the middle third.
2. How much torque should a stainless steel worm gear clamp be tightened to?
4.0–5.1 Nm (35–45 in·lb) for 12mm/1/2″ band; 3.0–4.5 Nm for 9mm band. Maximum recommended is 5.6 Nm.
3. What is the difference between W2 and W4 hose clamps?
W2 = stainless band/housing with plated screw. W4 = band, housing and screw all stainless (201/301/304). W5 = all 316. See Table 2.
4. What band width should I choose: 9mm or 12mm?
9mm for small hoses (~8–32mm OD) and tight spaces; 12mm/12.7mm for 20mm OD and above, silicone hoses, and industrial or marine duty.
5. Can one worm gear clamp cover multiple hose sizes?
Yes — each clamp has a continuous adjustment range (e.g. 20–32mm). Keep your hose OD in the middle third of the range.
6. Is a 304 or 316 stainless steel worm gear clamp better for marine use?
Choose W5 (all 316) for marine/coastal/chemical environments; 316 resists chloride pitting far better than 304. W4 (all 304) suits general automotive, plumbing and industrial use.
